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Generalized Ramsey Number


A generalized Ramsey number in the minimum-colors sense is the least number r(G,H,q) of colors needed for an edge coloring of a graph G in which every copy of a graph H receives at least q distinct colors. Copies need not be induced, and the coloring need not be a proper coloring. The parameter satisfies 2<=q<=|E(H)| (Lane and Morrison 2026). This differs from the Ramsey number convention, which fixes the number of colors and asks for the host size forcing a monochromatic copy.

For each fixed k>=3, Lane and Morrison (2026, Corollary 3) prove

 r(K_n,C_k,3)=n/(k-2)+o(n),

where K_n is a complete graph, C_k is a cycle graph, and o(n) denotes little-O notation as n->infty. Their Theorem 2 gives the same asymptotic value when every cycle graph with length between fixed integers k and l>=k must receive at least three colors. For k=3, the condition is precisely a proper coloring of the graph edges of K_n, so r(K_n,C_3,3) is its edge chromatic number.

Lane and Morrison (2026) also prove upper bounds for even cycles in the complete bipartite graph K_(n,n) using conflict-free hypergraph matchings.


See also

Edge Chromatic Number, Edge Coloring, Ramsey Number, Ramsey Theory

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References

Lane, A. and Morrison, N. "Generalized Ramsey Numbers via Conflict-Free Hypergraph Matchings." Elec. J. Combin. 33, P4.2, 2026. https://doi.org/10.37236/14492.

Cite this as:

Weisstein, Eric W. "Generalized Ramsey Number." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/GeneralizedRamseyNumber.html

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